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. 2017 Jan 24;112(2):376–387. doi: 10.1016/j.bpj.2016.12.013

Figure 3.

Figure 3

Relaxation kinetics of rabbit psoas myofibrils containing recombinant control, D137L, or D137L/G126R ααTm at 15°C. (A) Time course of full-force relaxation from maximal activation of representative control and D137L/G126R ααTm-reconstituted myofibrils, obtained by fast solution switching from pCa 4.5 back to a pCa 9.0 relaxing solution. The same traces as in Fig 2A were normalized and presented on an expanded timescale to show the kinetics of force relaxation. Dark gray trace: control ααTm myofibril (duration of slow phase: 129 ms; slow kREL = 1.7 s−1; fast kREL = 13.4 s−1). Light gray trace: D137L/G126R ααTm myofibril (duration of slow phase: 91 ms; slow kREL = 1.6 s−1; fast kREL = 38.5 s−1). (B) Mean values of the duration of slow-phase relaxation. (C) Mean values of the rate of the slow phase of relaxation (slow kREL). (D) Mean values of the rate of the fast phase of relaxation (fast kREL). Histogram columns: control (white), D137L (light gray), and D137L/G126R ααTm (dark gray) myofibrils. Bars above the columns are SEM, and the number of myofibrils is shown above the bars. ∗p < 0.0005 (Student’s t-test) versus the same parameter measured in control ααTm-reconstituted myofibrils. #p < 0.05 (Student’s t-test) versus the same parameter measured in control ααTm-reconstituted myofibrils. °p < 0.002 (Student’s t-test) versus the same parameter measured in D137L ααTm-reconstituted myofibrils.